 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  * Genady Beryozkin, me@genady.org - #getSuggestions implementation copied from HippieCompleteAction
  *******************************************************************************/
 package org.eclipse.ui.texteditor;

 import java.util.ArrayList ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;

 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.DocumentEvent;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IInformationControlCreator;
 import org.eclipse.jface.text.ITextViewer;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
 import org.eclipse.jface.text.contentassist.ICompletionProposalExtension;
 import org.eclipse.jface.text.contentassist.ICompletionProposalExtension2;
 import org.eclipse.jface.text.contentassist.ICompletionProposalExtension3;
 import org.eclipse.jface.text.contentassist.ICompletionProposalExtension4;
 import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
 import org.eclipse.jface.text.contentassist.IContextInformation;
 import org.eclipse.jface.text.contentassist.IContextInformationValidator;

 import org.eclipse.ui.IEditorInput;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IEditorReference;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.internal.texteditor.HippieCompletionEngine;

 /**
  * A completion proposal computer for hippie word completions.
  * <p>
  * Clients may instantiate.
  * </p>
  *
  * @since 3.2
  */
 public final class HippieProposalProcessor implements IContentAssistProcessor {

     private static final ICompletionProposal[] NO_PROPOSALS= new ICompletionProposal[0];
     private static final IContextInformation[] NO_CONTEXTS= new IContextInformation[0];

     private static final class Proposal implements ICompletionProposal, ICompletionProposalExtension, ICompletionProposalExtension2, ICompletionProposalExtension3, ICompletionProposalExtension4 {

         private final String fString;
         private final String fPrefix;
         private final int fOffset;

         public Proposal(String string, String prefix, int offset) {
             fString= string;
             fPrefix= prefix;
             fOffset= offset;
         }

         public void apply(IDocument document) {
             apply(null, '\0', 0, fOffset);
         }

         public Point getSelection(IDocument document) {
             return new Point(fOffset + fString.length(), 0);
         }

         public String getAdditionalProposalInfo() {
             return null;
         }

         public String getDisplayString() {
             return fPrefix + fString;
         }

         public Image getImage() {
             return null;
         }

         public IContextInformation getContextInformation() {
             return null;
         }

         public void apply(IDocument document, char trigger, int offset) {
             try {
                 String replacement= fString.substring(offset - fOffset);
                 document.replace(offset, 0, replacement);
             } catch (BadLocationException x) {
                 // TODO Auto-generated catch block
 x.printStackTrace();
             }
         }

         public boolean isValidFor(IDocument document, int offset) {
             return validate(document, offset, null);
         }

         public char[] getTriggerCharacters() {
             return null;
         }

         public int getContextInformationPosition() {
             return 0;
         }

         public void apply(ITextViewer viewer, char trigger, int stateMask, int offset) {
             apply(viewer.getDocument(), trigger, offset);
         }

         public void selected(ITextViewer viewer, boolean smartToggle) {
         }

         public void unselected(ITextViewer viewer) {
         }

         public boolean validate(IDocument document, int offset, DocumentEvent event) {
             try {
                 int prefixStart= fOffset - fPrefix.length();
                 return offset >= fOffset && offset < fOffset + fString.length() && document.get(prefixStart, offset - (prefixStart)).equals((fPrefix + fString).substring(0, offset - prefixStart));
             } catch (BadLocationException x) {
                 return false;
             }
         }

         public IInformationControlCreator getInformationControlCreator() {
             return null;
         }

         public CharSequence getPrefixCompletionText(IDocument document, int completionOffset) {
             return fPrefix + fString;
         }

         public int getPrefixCompletionStart(IDocument document, int completionOffset) {
             return fOffset - fPrefix.length();
         }

         public boolean isAutoInsertable() {
             return true;
         }

     }

     private final HippieCompletionEngine fEngine= new HippieCompletionEngine();

     /**
      * Creates a new hippie completion proposal computer.
      */
     public HippieProposalProcessor() {
     }

     /*
      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#computeCompletionProposals(org.eclipse.jface.text.ITextViewer, int)
      */
     public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int offset) {
         try {
             String prefix= getPrefix(viewer, offset);
             if (prefix == null || prefix.length() == 0)
                 return NO_PROPOSALS;
             
             List suggestions= getSuggestions(viewer, offset, prefix);
             
             List result= new ArrayList ();
             for (Iterator it= suggestions.iterator(); it.hasNext();) {
                 String string= (String ) it.next();
                 if (string.length() > 0)
                     result.add(createProposal(string, prefix, offset));
             }
             
             return (ICompletionProposal[]) result.toArray(new ICompletionProposal[result.size()]);
             
         } catch (BadLocationException x) {
             // ignore and return no proposals
 return NO_PROPOSALS;
         }
     }

     private String getPrefix(ITextViewer viewer, int offset) throws BadLocationException {
         IDocument doc= viewer.getDocument();
         if (doc == null || offset > doc.getLength())
             return null;
         
         int length= 0;
         while (--offset >= 0 && Character.isJavaIdentifierPart(doc.getChar(offset)))
             length++;
         
         return doc.get(offset + 1, length);
     }

     private ICompletionProposal createProposal(String string, String prefix, int offset) {
         return new Proposal(string, prefix, offset);
     }

     /*
      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#computeContextInformation(org.eclipse.jface.text.ITextViewer, int)
      */
     public IContextInformation[] computeContextInformation(ITextViewer viewer, int offset) {
         // no context informations for hippie completions
 return NO_CONTEXTS;
     }
     
     /*
      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getCompletionProposalAutoActivationCharacters()
      */
     public char[] getCompletionProposalAutoActivationCharacters() {
         return null;
     }
     
     /*
      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getContextInformationAutoActivationCharacters()
      */
     public char[] getContextInformationAutoActivationCharacters() {
         return null;
     }
     
     /*
      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#getContextInformationValidator()
      */
     public IContextInformationValidator getContextInformationValidator() {
         return null;
     }

     /**
      * Return the list of suggestions from the current document. First the
      * document is searched backwards from the caret position and then forwards.
      *
      * @param offset
      * @param viewer
      * @param prefix the completion prefix
      * @return all possible completions that were found in the current document
      * @throws BadLocationException if accessing the document fails
      */
     private ArrayList createSuggestionsFromOpenDocument(ITextViewer viewer, int offset, String prefix) throws BadLocationException {
         IDocument document= viewer.getDocument();
         ArrayList completions= new ArrayList ();
         completions.addAll(fEngine.getCompletionsBackwards(document, prefix, offset));
         completions.addAll(fEngine.getCompletionsForward(document, prefix, offset - prefix.length(), true));

         return completions;
     }

     /**
      * Create the array of suggestions. It scans all open text editors and
      * prefers suggestions from the currently open editor. It also adds the
      * empty suggestion at the end.
      *
      * @param viewer
      * @param offset
      * @param prefix the prefix to search for
      * @return the list of all possible suggestions in the currently open
      * editors
      * @throws BadLocationException if accessing the current document fails
      */
     private List getSuggestions(ITextViewer viewer, int offset, String prefix) throws BadLocationException {

         ArrayList suggestions= createSuggestionsFromOpenDocument(viewer, offset, prefix);
         IDocument currentDocument= viewer.getDocument();

         IWorkbenchWindow window= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
         IEditorReference editorReferences[]= window.getActivePage().getEditorReferences();

         for (int i= 0; i < editorReferences.length; i++) {
             IEditorPart editor= editorReferences[i].getEditor(false); // don't create!
 if (editor instanceof ITextEditor) {
                 ITextEditor textEditor= (ITextEditor) editor;
                 IEditorInput input= textEditor.getEditorInput();
                 IDocument doc= textEditor.getDocumentProvider().getDocument(input);
                 if (!currentDocument.equals(doc))
                     suggestions.addAll(fEngine.getCompletionsForward(doc, prefix, 0, false));
             }
         }
         // add the empty suggestion
 suggestions.add(""); //$NON-NLS-1$

         List uniqueSuggestions= fEngine.makeUnique(suggestions);

         return uniqueSuggestions;
     }

     /*
      * @see org.eclipse.jface.text.contentassist.ICompletionProposalComputer#getErrorMessage()
      */
     public String getErrorMessage() {
         return null; // no custom error message
 }
 }

